1. Field of Invention
The present invention relates to a fixed angle centrifuge rotor having a cover with a support structure for supporting containers carried within the rotor.
2. Description of Prior Art
A centrifuge rotor may be classified on the basis of the angle defined between the rotor's vertically extending axis of rotation and the axis extending through each sample container-receiving cavity formed in the rotor body. A rotor in which the axis of the cavity lies at a predetermined acute angle (typically on the order of twenty degrees) relative to the rotor's vertical axis of rotation is termed a "fixed angle" rotor. U.S. Pat. No. 4,202,487 (Edwards) is believed a representative example of a fixed angle rotor. A rotor in which the axis of the cavity is parallel to the rotor's axis of rotation is known as a "vertical" rotor. U.S. Pat. No. 4,944,721 (Carson), assigned to the assignee of the present invention, discloses a vertical rotor.
When using either a fixed angle or a vertical rotor each of the sample containers must be individually capped or sealed to contain liquid during centrifugation. Moreover, each of the sealed or capped containers must be constrained within its respective cavity. In cases where the top of the container extends above the mouth of the cavity the performance of the rotor must be limited. Otherwise, the portion of the container above the cavity, which can not support its own mass under high centrifugal loads, may deform or fail.
Various container capping and constraining arrangements for containers have been proposed. In the vertical rotor case a threaded closure member is used to close the upper end of the container-receiving cavity. U.S. Pat. No. 4,166,573 (Webster) and U.S. Pat. No. 3,998,383 (Romanauskas), both assigned to the assignee of the present invention, disclose a form of cavity closure member. The above-referenced Carson patent discloses a cover for a vertical rotor having a container support structure for supporting the upper end of a container when the same extends above the mouth of the vertical cavity.
In a fixed angle environment U.S. Pat. No. 4,304,356 (Chulay et al.) discloses a cap that once inserted into the cavity "floats" on the tube disposed in the cavity. This type of arrangement requires the clinician to double the number of steps it takes to perform a centrifugation protocol, since in addition to inserting and removing the sample containers, the "caps" must be removed as well.
In view of the foregoing it is believed advantageous to provide a cover for a fixed angle centrifuge rotor that integrates a container support structure into the rotor cover.